In the photographic field there has been a trend toward miniaturizing the size of cameras and in recent years relatively small and inexpensive cameras have been designed which can easily fit into a pocket. These "pocket" type cameras have become quite popular and efforts have been made to incorporate features heretofore available only in larger-sized cameras into pocket cameras.
One such important feature which has been incorporated in small pocket cameras is the ability to provide a plurality of picture taking or objective lenses. For example, lenses of different focal lengths such as a telephoto lens and a normal lens can be used, or lenses with special effects such as a portrait lens can also be desired. It is further desirable, however, with such a plurality of objective lenses, to provide a manner of automatically altering the viewfinder lens system so that it will truly correspond to the optical characteristics of the selected objective lens. With a telephoto and normal lens set, for example, the magnification and field of view of the subject as seen through the viewfinder should correspond to the magnification and field of view of the subject as recorded by the camera objective lens being used.
Examples of cameras using a multiple objective lens and corresponding multiple viewfinder lens system are shown in Tiranti, U.S. Pat. Nos. 2,812,698, and Mueller, 2,653,528. Both of these systems, however, are quite complex, bulky and expensive, and are thus unacceptable for the small pocket-type cameras. Other attempts at providing viewfinder lens systems which correspond to the optical characteristics of selected picture taking lenses are disclosed in Suzuki et al, U.S. Pat. Nos. 3,836,934, Baisch et al, 3,961,344 and in German DT-PS No. 815,441. In Suzuki, and the German patent, however, a supplementary lens is interposed into the optical path of the objective lens and viewfinder lens. This system, by adding an additional lens to an existing system, would not provide as high an optical quality as in systems where the lenses are actually changed and/or replaced. As a general rule, the more lenses in line with the optical paths the greater the chances are for distortion and the poorer the quality. Furthermore, by merely adding a lens, the variance or change in magnification which can be achieved is relatively slight. The Baisch patent discloses a mirror system which rotates in and out of position in order to provide a dual field viewfinder arrangement. As such, separate viewfinder lenses directly corresponding and fitting to the objective lenses are here also not provided and the optical variation of the system is relatively small.
For the modern small type pocket cameras it is thus desirable to have the added feature of multiple objective lenses with a viewfinder lens system that truly corresponds to the optical characteristics of such multiple objective lenses. It is further desirable to have a high quality viewfinder system which is enhanced if separate lenses are provided corresponding to each of the optical lenses being used; the quality would be high, and a relatively large change in optical magnification can be achieved. Furthermore, it is necessary in such a camera to have the multiple objective and viewfinder lens systems and their interconnecting linkages relatively compact. Finally, it is a further necessity to keep the expense of any added features, such as the aforementioned dual lens and viewfinder system, to a minimum both from the standpoint of additional components and from the standpoint of assembly time. In this manner, it would obviously be a distinct advantage to incorporate such a system with a relatively small number of components which, besides being reliable and easy to operate, would be inexpensive and simple in construction.